Ong Kah Sin
Fisheries Research Institute, Penang
Rabihah Mahmood
Department of Fisheries, Kuala Lumpur
I. INTRODUCTION
Mollusc production in Malaysia includes production of cephalopods, gastropods and bivalves from capture fisheries based on natural stocks, and production of bivalves from aquaculture systems based almost exclusively on natural spats. Although cephalopods, particularly of the families Loliginadae and Sepiidae, are of great commercial importance accounting for some 20,000 MT landed a year, and several species of gastropods are collected by inshore fishermen, this report focuses on the bivalve molluscs, especially those that are produced from aquaculture operations.
II. MAJOR BIVALVE SPECIES IN MALAYSIA
Bivalve molluscs in Malaysia consist of a great variety of species. A total of 185 species from 44 families have been listed (Morris and Purchon, 1981) and the major species of commercial importance have been reported more recently (Ng et al., 1982; Wong and Ng, 1986).
The bivalve species that are landed and of commercial importance at present include the following:
| - Cockles: | Anadara granosa, A. antiquata |
| - Carpet/Venus clam: | Paphia undulata, Meretrix meretrix |
| - Mussels: | Perna viridis, Modiolus philippinarium |
| - Oysters: | Ostrea folium, Saccostrea cucullata, Crassostrea belcheri, C. iredalei, Pinctada sp. |
| - Razor clams: | Solen brevis, Cultellus lacteus, Pharella acuminata |
| - Fan shells: | Pinna bicolor, P. incurva |
| - Giant clam: | Tridacna spp. (especially in Sabah) |
| - Others: | Orbicularia orbiculata, Geloina erosa, Placuna placenta, Pholas orientalis, Donax faba, Pecten sp. |
III. STATUS OF BIVALVE PRODUCTION AND MARKETING IN MALAYSIA
There are no statistics available on the annual production of bivalves by species. The Annual Fisheries Statistics of the Department of Fisheries Malaysia however provides production figures of shelled molluscs (largely cockles) which show an increasing trend until a peak production of 121,000 MT in 1980 and thereafter a declining trend for cockles to 40,794 MT in 1987 and 34,867 MT in 1988. On the other hand, mussel culture production recorded a significant increase from 248.5 MT in 1986 to 1,368 MT in 1988.
3.1 Cockle production
The cockle, Anadara granosa, is by far the most important aquaculture species in Malaysia (Ong, 1981, 1983; Ong and Liong, 1988); its production accounts for more than 85% of the total aquaculture production. This has been made possible by the abundant supply of natural seeds, extensive areas of mudflats on the sheltered west coast of Peninsular Malaysia suitable for cockle cultivation, and the favourable market demand. Recent research conducted by the Fisheries Research Institute has verified the optimum duration for culture in order to obtain maximum production (Ng, 1986), achieved the artificial propagation of the cockle under laboratory conditions (Kamal Zaman, 1986), and determined possible new sites for cockle culture production.
3.2 Carpet clam production
The carpet clam, Paphia undulata, is the second most important bivalve in Malaysia in terms of total production. At present, the bulk of Paphia landings is derived from an inshore dredge fishery operating seasonally in the northern part of the west coast of Peninsular Malaysia from Perlis to penang. Estimated potential annual production is 20,000 MT. As Paphia does not stay live and fresh for long once it is landed, the landings are usually washed and shucked after boiling and then frozen in plastic bags before being shipped to canneries. Some landings are sent directly to canneries, and only a small portion is sold fresh in local markets.
3.3 Mussel production
By aquaculture production, Perna viridis would rank as the second most important bivalve species in Malaysia. Based on the work carried out by the Fisheries Research Institute (Choo, 1979), and the support services provided by the government (Ong, 1985; Tan, 1985; Ubaidillah, 1985), mussel culture as well as other systems of aquaculture have shown significant development in recent years. Mussel culture has now spread from the Johore Straits to other parts of the country, especially to Melaka and Perak where natural spats are available, as well as to other parts where natural spats are not available, by the transplantation of young mussels collected usually on polypropylene ropes from the straits of Johore. With the production system already developed and mussel culture now spreading to other parts of the country, production is projected to considerably increase in the near future possibly surpassing that of Paphia.
3.4 Oyster production
The oysters comprise the third group of bivalves of commercial importance which are cultured as well as collected from the wild. According to Angell (1988), much of the production is derived from intertidal stocks of Saccostrea cucullata. However other species are important in specific localities, e.g. C. belcheri in Muar, Johor; Batu Lintang, Kedah and Tawau, Sabah; C. iredalei in Sungai Merchang and Kuala Setiu, Trengganu; Ostrea folium in Langkawi. Kedah and Pinctada sp. in Semporna, Sabah where it is cultured commercially for pearls.
Angell (1988) estimated the annual production of shucked oyster meat for five centres in the west coast of Peninsular Malaysia (Langkawi, Penang, Pangkor, Melaka and Muar) at 127.2 MT. Based on this, it is estimated that the total production for the whole country is at least 200 MT. Although the production is still small, oysters constitute the most number of species of any single group among the major groups that are of coastal aquaculture importance in Malaysia.
The feasibility of oyster culture, particularly of Ostrea folium in Langkawi, Kedah has been reported by Ng (1978), while the experimental culture of C. belcheri in Sabah has been reported by Chin and Lim (1978). Current research and development on oyster culture in Malaysia is carried out with the support of the Bay of Bengal Fisheries Development Programme. The culture of Ostrea folium is being successfully carried out on an expanded scale, while considerable numbers of spat of C. iredalei have been collected at Sungai Merchang and Kuala Setiu, Trengganu for culture in situ as well as for transplantation to other parts of the country.
3.5 Production of other bivalve species
No statistics are available on the quantities of the other bivalve species of commercial importance that are landed and marketed in various parts of the country. Many of these species, especially the razor clams, are of high value and are often served in popular seafood restaurants. Their production is inadequate to meet the growing demand.
3.6 Bivalve marketing
The prices of bivalves are relatively low. The prices for both major cultured species i.e. cockle and mussel are also stable. However, the wholesale price of cockle was relatively high in 1984, at M$ 0.50/kg, but declined to M$ 0.44 in 1986 and dropped further to M$ 0.33 in 1987 and 1988. During the same period, the retail price of cockle dropped from M$ 0.71/kg in 1984 to M$ 0.62/kg in 1988, The margin between the wholesale and retail prices ranged from 42 – 88%. This covered marketing and transport costs and profit.
In the case of mussel, the average wholesale price in 1987–88 was M$ 0.30–0.35/kg and the retail price M$ 0.66/kg. With the limited production and its growing popularity, retail price of mussel in some areas is now M$ 1.00/kg.
The bulk of the bivalves in Malaysia is marketed in the fresh state. A considerable portion of the bivalves produced is also exported, mostly in the fresh but also in the chilled and frozen forms. The volume of bivalve exports (mostly cockles) has shown an increase in recent years, from 29,606 MT (valued at M$ 17 million) in 1985 to 37,553 MT (valued at M$ 37 million) in 1987. The exports are mostly to Singapore, Thailand and Japan.
IV. PROBLEMS OF BIVALVE PRODUCTION
While the potential for increasing bivalve and generally all aquaculture production in Malaysia is considered to be very good, several constraints have been identified in the development (Ong, 1983; Ong and Liong, 1988; Ng, 1987; Wong and Ng, 1986); Department of Fisheries Malaysia, 1988). These include:
4.1 Unreliable spat supply
Bivalve production for food in Malaysia is still totally dependent on natural seeds. While spats of the cockle Anadara granosa have generally been adequate for culture and transplantation, culture projects sometimes have to wait for several weeks and even months before spats are available, and often the supply is inadequate or the spat settlement density may not be high enough. In the case of oysters, only the spats of Ostrea folium and C. iredalei have so far ben collected in sufficient quantities while the spats of the highly valued C. belcheri have only been collected in small numbers. Attempts have been made and are being intensified to artificially propagate C. belcheri but only limited success has been achieved.
4.2 Lack of knowledge
While there is a great diversity of bivalve species in Malaysia, existing knowledge on the biology of even the more important species which is necessary for sound management of the natural stocks, and on the technology of artificial propagation, is still inadequate. Only the culture of cockles can be said to have attained significant production on a commercial scale while the culture of mussels has reached an expansion phase. The culture of oysters on a commercial scale is still under research and development, with the exception of the pearl oyster, Pinctada sp., which has been successfully propagated and cultured on a commercial scale for the production of pearls. Development of the technology for the artificial propagation of oysters, especially for the high-value species C. belcheri, on a commercial scale could lead to a sustained increase in local oyster production. This could reduce the considerable import of oysters, amounting to some 250 MT in 1987, mostly from South Korea (Annual Fisheries Statistics).
4.3 Inadequate consumer demand/market price
While bivalve production is generally promoted on account of its being able to produce good animal protein at relatively low cost, the low price can also act as a constraint to the economic production of some species. For example, the culture of the mussel Perna viridis in Malaysia could be expanded at a more rapid rate if there was a greater consumer demand and market price for this product.
The price of the bivalve at the culture site which is often far from the main market centres can also be much lower than the final retail price, as in the case of Ostrea folium cultured in Langkawi, where geographical remoteness and broker monopsony have been determined to be the two main factors that keep prices low (Angell, 1988).
4.4 Site/environmental problems
Although geographical, climatic and environmental conditions are generally very conducive for aquaculture development in Malaysia, including the existence of extensive sheltered mudflats on the west coast of Peninsular Malaysia for the on-bottom culture of the cockle, suitable sites are not easily available for culture operations due to the procedures involved in acquiring lease of the coastal sites. Coastal aquaculture is still a relatively new development and there are no standard regulations governing the lease of coastal sites as administration of land including coastal areas falls under the respective State jurisdictions.
With increasing urban and industrial development, often requiring land-fill and reclamation of possible culture sites, aquatic pollution due to domestic and industrial effluent, and increased sediment load arising mining and land development schemes, certain areas have been rendered less suitable or even totally unsuitable for the culture of bivalve or other species.
Shellfish, particularly the consumption of semi-cooked cockles/clams, produced in some areas have on many occasions been suspected to cause various diseases including cholera, typhoid, dysentery and hepatitis A. Fear of contracting disease from eating shellfish is believed to have also contributed to the decline in the consumption and production of shellfish (Department of Fisheries Malaysia 1988). Commercial-scale operation of depuration plants has yet to be established in Malaysia in order to produce shellfish, particularly cockles that may be safe to consume in the blanched or semi-cooked state, as preferred by most consumers.
In the coastal waters of the west coast of Sabah, production of wholesome shellfish is affected by sporadic blooms of the toxic dinoflagellate Pyrodinium bahamense var. compressa. The toxins from this organism were found to be accumulated by various groups of shellfish including clams, mussels, oysters and cockles (Wong and Ting, 1984). Since the first and the worst red tide outbreak in 1976, over 300 paralytic shellfish poisoning cases and several deaths have been reported in Sabah (Ting and Wong, 1989).
V. SUPPORT SERVICES AND PROGRAMMES ON BIVALVE PRODUCTION AND SANITATION
The Government is committed towards developing aquaculture into a major industry by the turn of the century in line with the National Agriculture Policy (Ubaidillah, 1985) and included in the overall development programme is the expansion of bivalve, particularly cockle and mussel production. Government inputs will include the provision of supporting institutional services including research, extension, training, resource management, marketing services and fiscal incentives (Ong, 1985; Tan, 1985; Ubaidillah, 1985).
The main support services and programmes pertaining to bivalve production and sanitation are as follows:
5.1 Research and development on bivalve production
The ongoing research and development programme on bivalve production in Malaysia which covers the cockle, mussel and oysters, includes the following activities and objectives:
Results of recent studies on bivalve production and marketing of oyster in Malaysia have been reported (Angell, 1988; Devakie, 1986; Kamal Zaman, 1986; Ng, 1986).
5.2 Development of cockle depuration system
In view of increasing consumer concern over shellfish sanitation, the frequent occurrence of high faecal coliform counts in samples of cockles from several localities and the sanitary standards imposed on bivalve imports by many countries, the Fisheries Research Institute, has embarked since June 1986 on establishing a depuration system for cockles. The pilot programme, carried out with the support of the ASEAN Food Handling Bureau sponsored under the ASEAN-Australia Economic Cooperation Programme, has succeeded in setting up an effective and practical pilot-scale depuration system using two 30W ultraviolet lamps with peak emission at 2537° A for sterilization of the water in the closed circulating system. It was found that purification of the cockles to the required levels (FC-MPN/g) could be achieved within 36 hours of the process, even with cockles having an initial level of contamination as high as 1,260 FC-MPN/g (Ismail, 1988).
Based on the pilot system, the Fisheries Research Institute, with the technical support of the Technology Branch of the Department of Fisheries, has successfully built a semi-commercial system in early 1989, capable of depurating 1.5 MT of cockles per cycle. The Department is now promoting the commercial adoption of the depuration system.
Figures 1a-1d show observed patterns of faecal coliform reduction in the depuration system for cockles with different initial levels of contamination. While some samples of cockles have high initial faecal coliform counts exceeding 500 and occasionally also 1000 FC-MPN/g and would require 24–30 hours depuration, most cockle samples have been found to be sufficiently depurated to meet sanitary standards within 20 hours. Some samples of cockles have also been found to have very low faecal coliform levels which would not require depuration. However as cockles are usually eaten in the semi-cooked state, it would be advisable to be assured of the sanitary condition beforehand by means of depuration and monitoring of the faecal coliform count.
Figure 1a. Cockle depuration for sample
Figure 1b. Cockle depuration for sample
Figure 1c. Cockle depuration for sample
Figure 1d. Cockle depuration for sample
5.3 Monitoring of pollutants in shellfish
For several years now, the Fisheries Research Institute in Glugor, Penang has carried out monitoring of the levels of heavy metal (cadmium, mercury, copper, lead, zinc, tin, arsenic) and other pollutant in fish particularly shellfish sampled from various localities throughout the country. The initial phase of this biomonitoring programme received technical assistance from the German Agency for Technical Cooperation. Results from the studies carried out so far (Jothy et al., 1983; Liong, 1983; Shahunthala, 1986 & 1989) show that the heavy metal values determined were well below the maximum permissible limits set by the Food Regulations 1985 Malaysia; the only exception was for the values of lead determined for cockles from two localities in Perak (Kuala Gula and Bagan Panchor). However, based on the estimated consumption of cockle in Malaysia, it has been calculated that the weekly intake for the Malaysian consumer would be well within the WHO-defined acceptable limits. Therefore, there is no acute danger for the population (Department of Fisheries Malaysia, 1988).
With regard to the red-tide problem, Sabah Fisheries Department carries out a regular PSP surveillance programme using standard procedures for the bioassay of toxin levels and a standard quarantine level based on Canadian epidemiological studies (Wong & Ting, 1984), so that the general public could be given early warning.
5.4 Safeguarding environmental quality and sanitary standards
The major legislation to protect the environment is the Environment Act 1974. The Ministry of Science, Technology and the Environment is empowered to prescribe regulations and standards relating to aquatic pollution. The Department of Fisheries has carried out monitoring of water quality in selected localities and proposed water quality standards for fishery purposes (Liong, 1984).
Regulatory control of shellfish is covered under the Food Act 1983 and the Food Regulations 1985 (Sharri, 1988). Guidelines on enforcement activities are produced by the Food Quality Control Unit of the Ministry of Health Malaysia.
5.5 Resource conservation
The Department of Fisheries is also promoting resource conservation, including imposing size regulations on the cockles that may be collected for transplantation (Fisheries Act, 1985). The setting up of marine parks in various parts of the country, and the development of artificial reefs have also helped in the conservation of fish and shellfish resources. Various species of bivalves, especially the oyster Saccostrea cucullata have been found in large numbers in all the reefs.
VI. FUTURE PROGRAMMES
The important existing programmes will be continued and special attention accorded in future to the following:
6.1 Promotion of depuration
The Department of Fisheries will intensify its efforts to promote the setting up of depuration plants in various parts of the country. Already, information on cockle depuration has been disseminated through TV, press and departmental publications. Short training courses are being planned for interested agencies, fishermen's associations and the private sector.
The setting up of commercial scale depuration plants would also need support by the certification of approved depuration plants and issue of certified labels for depurated cockles and other shellfish from these plants, as in the case of oyster depuration in Australia and other countries. According to Ayres (1988), “it will be found that product from such establishments fetches premium prices in hotels, restaurants, etc. and thereby acts as an incentive to both the operator and others in the industry to copy the example”.
6.2 Hatchery programme
In view of the unreliable supply of bivalve seeds from the wild, further research and development need to be carried out to develop a practical and cost effective system for the artificial propagation of the commercially important species of bivalves, particularly the high-value Crassostrea belcheri. Already, work on this species is being carried out by the Sabah Fisheries Department and the Universiti Sains Malaysia with the support of IDRC.
6.3 New bivalve species for culture
With the advances made on the cultivation of giant tridacnid clams in other parts of Asia and the Pacific (Copeland and Lucas, 1988), and the over-exploited state of the giant clam resource in Malaysian waters, it appears timely to carry out experiments on the possibility of giant clam culture in Malaysia. Initial work could involve the transplantation of young giant clams from existing production centres. Technical assistance and training opportunities in clam mariculture would be most welcome, in order to enable Malaysians to proceed on a proper footing.
6.4 Biotechnology in bivalve production
According to Baker (1989), marine biotechnology has a tremendous potential and “essential role in assisting developing countries to solve, within available financial resources, some of their most pressing problems such as food supply, pollution control and disease control”. It is therefore necessary to develop the relevant capability within the Fisheries Research Institute in the near future, so that the development of bivalve culture and aquaculture production in general can be accelerated through the application of marine biotechnology.
ACKNOWLEDGEMENT
Grateful acknowledgement is due the Director-General of Fisheries Malaysia, Dato Shahrom Bin Haji Abdul Majid for his kind support; to NACA and the FAO/UNDP Regional Seafarming Development and Demonstration Project as well as the host authorities for the opportunity to attend this workshop.
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